[PATCH] staging: zcache: fix cleancache crash

[Dan Magenheimer]

> From: Seth Jennings [mailto:sjenning at linux.vnet.ibm.com]
> Sent: Tuesday, September 13, 2011 1:19 PM
> To: gregkh at suse.de
> Cc: devel at driverdev.osuosl.org; linux-mm at kvack.org; ngupta at vflare.org; linux-kernel at vger.kernel.org;
> francis.moro at gmail.com; Dan Magenheimer; Seth Jennings
> Subject: [PATCH] staging: zcache: fix cleancache crash
> 
> After commit, c5f5c4db, cleancache crashes on the first
> successful get. This was caused by a remaining virt_to_page()
> call in zcache_pampd_get_data_and_free() that only gets
> run in the cleancache path.
> 
> The patch converts the virt_to_page() to struct page
> casting like was done for other instances in c5f5c4db.
> 
> Based on 3.1-rc4
> 
> Signed-off-by: Seth Jennings <sjenning at linux.vnet.ibm.com>

Yep, this appears to fix it!  Hopefully Francis can confirm.

Greg, ideally apply this additional fix rather than do the revert
of the original patch suggested in https://lkml.org/lkml/2011/9/13/234 

Acked-by: Dan Magenheimer <dan.magenheimer at oracle.com>

> ---
>  drivers/staging/zcache/zcache-main.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
> index a3f5162..462fbc2 100644
> --- a/drivers/staging/zcache/zcache-main.c
> +++ b/drivers/staging/zcache/zcache-main.c
> @@ -1242,7 +1242,7 @@ static int zcache_pampd_get_data_and_free(char *data, size_t *bufsize, bool raw,
>  	int ret = 0;
> 
>  	BUG_ON(!is_ephemeral(pool));
> -	zbud_decompress(virt_to_page(data), pampd);
> +	zbud_decompress((struct page *)(data), pampd);
>  	zbud_free_and_delist((struct zbud_hdr *)pampd);
>  	atomic_dec(&zcache_curr_eph_pampd_count);
>  	return ret;
> --
> 1.7.4.1
>